Outcomes of vitrified early cleavage stage and blastocyst stage embryos in a cryopreservation program Evaluation of 3150 warming cycles

The delivery rate achieved after the vitrification of early cleavage- and blastocyst-stage embryos is not affected by the embryo developmental stage or any other variable related to the warming cycle.


Ana Cobo, Ph.D., María José de los Santos, Ph.D., Damià Castellò, Ph.D., Pilar Gàmiz, Ph.D., Pilar Campos, M.L.T., José Remohí, M.D.

Vol 98, Issue 5, Pages 1138-1146.e1



To assess the outcome achieved after Cryotop vitrification of both early cleavage and blastocysts stage and to determine whether the embryo developmental stage and embryo quality as well as the origin of the embryos (ovum donation cycles, patients own oocytes) and the endometrial preparation for the embryo transfer had any effect on the final outcome.


Observational study.


Private university-affiliated IVF center.


Women undergoing 3,150 warming cycles whose embryos were vitrified due to various reasons.


Vitrification by the Cryotop open device.

Main Outcome Measure(s):

Delivery rate (DR) per warming cycle.


Survival rate was 95% (N=5722 out of 6019 embryos). The percentage of intact embryos at warming, showing 100% blastomere-survival, was 93% (CI95% 90.1-95.3) for day-2 and 95% (CI95% 95.0% 94.3-95.7) for day-3. 3057 embryo-transfers (ET) were performed (ET cancellation rate=3%). The DR/warming cycle was 32.5% (CI95% 30.9-34.2). Slight differences in survival rate were found (94.9% (CI95% 93.0-96.8) for day-2; 94.2% (CI95% 93.4-94.9) for day-3; 95.7% (CI95% 94.5-96.9) for day-5 and 97.6% (CI95% 96.9-98.6) for day-6) (p


Highly successful cryopreservation of all embryo developmental stages is possible with the use of the Cryotop system. There are no any clear variable exerting a negative effect on the survival and delivery rates.

Read the full text at: http://www.fertstert.org/article/S0015-0282(12)01843-2/fulltext

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